Photographic light control device



Mamh 21, 1950 G. L. ABRUMS PHOTOGRAPHIC LIGHT CONTROL DEVICE 3 Sheets-Sheet 1 Filed March 14, 1947 Arman [r5 G. L,- ABRUMS PHOTOGRAPHIC LIQfIT CONTROL DEVICE 5 Sheets-Sheet 2 Filed March 14, 1947 m: 4 W m; 6

March 21, 1950 G. ABRUMS PHOTOGRAPHIC LIGHT CONTROL DEVICE 3 Sheets-Sheet 3 Filed March 14, 194'? INVENTOR. flaleo/vs J z W j wires l3 and I4 connected to a male plug mespective plug terminals |5.and l6...

Patented Mar. 21, 1950 UNITED STATES PATENT OFFICE PHOTOGRAPHIC LIGHT CONTROL DEVICE George Abrums, Jacksonville, Fla. v Application March 14, 1947, Serial No. 734,297

2 Claims. (01. 315491) This invention relates to control devices for photographic illumination sources and more particularly to a device for synchronizing the operation of a plurality of flashlight or floodlight lamps with the operation of a camera shutter.

A main object of the invention is to provide a novel and improved control system for con trolling a plurality of photofiood lamps'or the like, either alone or in combination with a plurality of photoflash lamps or the like, synchronously with the opening of one or more camera shutters for obtaining a photographic exposure, said system being simple in structure, easy to operate and reliable in performance.

A further object of the invention is to provide an improved electrical control system for the sources of illumination in photography, the system providing synchronization of peak intensity of all the lamps in the illumination source with the opening of the camera shutters, despite the fact that some lamps would reach peak intensity ahead of other lamps in the source if all the lamps were simultaneously energized, the system functioning to retard the energization of the former lamps so that all the lamps reach peak intensity at the same instant, said instant being that at which the camera shutter is opened.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompany- 3 ing drawings, wherein:

Figure 1 is a schematic wiring diagram illustrating the electrical layout of a lamp control system for photography constructed in accordance with the present invention.

Figure 2 is a schematic wiring diagram of an auxiliary lamp control unit employed with the system of Figure 1. Figure 3 is an elevational view of'a thermal switch adapted to be employed in the control system of Figure '1.

Figure 4 is a top plan View of an alternative embodiment of a thermal switch adapted 'to be employed in the control system of Figure 1. Referring tothe drawings, and more particularly'to Figure 1, designates a camera having a conventional shutter switch I2 actuated by the opening of the shutter to close the switch contacts. The shutter mechanism has'conven'tional means, not shown,'to close the switch contacts momentarily a fraction of a second before the :shutter is opened. Said contacts are normally open. The shutter switch 2 is provided with lead avin The illumination apparatus comprises a 'bank of photoflood lamps, or the like, shown at l1, l8, and I9, normally connected in series, and arranged to be connected in parallel by the energization of a relay 2!]. Relay 20 has a solenoid winding 2| and three sets of normally open contact pairs shown respectively at 22, 23, 24, 25, and 26, 21, which are simultaneously closed when the solenoid winding is energized.

The alternating current line wires are shown at 28 and 29, and connected across said wires, is a pilot lamp 312. Line wire 29 includes a control switch 3|, which is located beyond the connection to pilot lamp 30 so as not to afiect said pilot lamp. Connected across said line wires beyond switch 3| is a female receptacle or socket 32. One terminal of lamp 1 l is connected to line wire 29 by a wire 33. The other terminal of lamp I'! is connected by a wire 34 to contact 23 of the relay 20. One terminal of lamp I8 is connected by a wire 35 to wire 34 and the other terminal is connected by a wire 36 to a wire 37, leading to contact 24 of the relay. Line wire 29 is connected to contact 25 of the relay. Line wire 28 is connected to contact 22 of the relay. One terminal of lam I9 is connected by a wire 33 to line wire 28 and the other terminal thereof is connected to wire 31.

It will be seen from Figure 1 that when switch 3| is closed lamps I8 and I9 will be energized in series from the line wires 28 and 29 and will glow at low brilliance. However, when the contact pairs 22, 23 and 24, 25 are closed the lamps will be energized in parallel and will be at maxi mum brilliance.

Connected across line wires 28 and 29 beyond the switch 3| by wires 39 and 40 is the primary 4| of a step-down transformer 42. One terminal of the secondary 43 of the transformer is connected by a wire'44 to a terminal of the solenoid winding 2|. The other terminal of the secondary is connected by a wire 45 to one terminal of a rheostat 46. The other terminal of the rheostat is connectedby a wire 4'! to a wire 48. Connected to wire 48 is a female jack terminal 49 adapted to make contact with the male plug terminal l5. The second female jack terminal 50 is adapted to make contact with male plug terminallfi, and is connected by a wire 5| to the remaining terminal of solenoid winding 2|. Conwires 53 and are the, femalecontacts55 and 3 55 of a second female jack 5! whose purpose will be presently described.

A wire 58 connects wire 5| to relay contact 21. Connected to relay contact 26 by a wire 59 is the bimetallic electrically conducting contact arm 50 of a thermal switch 6|. Normally engaging arm 60 is a stationary contact 62 connected through a heater winding 63 wound around but insulated from arm 60 to a wire 64 which is connected to wire 45. Thermal switch 6! has another stationary Contact 65 adapted to be engaged by contact arm 60 as the arm flexes due to heating thereof. The arrangement is such that stationary contact 62 will remain in contact with arm Bi! for a short period of time after arm Bil engages the second stationary contact 65.

Contact 65 is connected by a wire 66 to a wire 61'. One end of wire 61 is connected to one terminal 68 of a female receptacle or socket SQ. The other end of wire 6'! is connected to a female contact "ill of a female jack H. The other terminal 12 of socket 69 is connected by a wire 13 to wire 44. The other terminal 14 of jack H is connected by a wire 15 to wire 13.

In operation of the system shown in Figure l,

when switch 12 of the camera shutter mechanism is momentarily closed, an energizing circuit for solenoid winding 2| is momentarily established comprising wire 44, connected to one terminal of transformer, secondary 3, solenoid winding 2!, wire 51, jack contact 50, plug contact 16,

wire 14, switch [2, wire [3, plug contact i5, jack contact 49, wire 48, wire 47, rheostat 45, and wire 45. This connects the lamps in parallel as above explained by closing the contact pairs 22,

. 23 and 24, 25. Contacts 26 and 2'! also close and establish a holding circuit for the solenoid winding 2| comprising wire 64 connected to wire 15 at the transformer secondary, heater winding 63,

' stationary contact 62, bimetal arm 60, wire 59,

contacts 26 and 21, wire 58, solenoid winding 2! and wire 44 connected to the other transformer secondary terminal. After a short time period, during which the camera shutter is open and the lamps l7, l8 and l9 are operating at full brilliancy to make the photographic exposure,

bimetal arm Bil flexes away from contact 62 and thereby breaks the holding circuit for solenoid winding 2!. The relay thereupon becomes deenergized and the three sets of contacts thereof open, causing the lamps l1, l8 and H! to return to their original series connection.

The above-described cycle of operation is employed where lamps l1, l8 and [9 are of the photoflood or similar type. and the timing of switch l2 with respect to the camera shutter is adjusted so that the lamps may reach their peak ibrilliancy just before the shutter is opened wide. It is frequently desirable to employ auxiliary photoflood lamps. For this purpose an auxiliary unit such as is shown in Figure 2 is employed with the main apparatus of Figure 1.

The auxiliary unit comprises photoflood lamps 16, TI, and 18, normally connected in series and arranged to be connected in parallel by a relay '19. Relay 19 has a solenoid winding 89 whose terminals are connected by respective wires 8| and 82 to the respective male plug terminals 83 and 84 of a male jack plug 35. Relay 79 has two sets of contacts, shown at 86., 81 and 88, 89, said contacts being normally open and being closed responsive to energization of solenoid winding 80.

. 16 is connected by a wire 93 to wire SI and the iii) 1 subject.

plugged into jack "H.

other terminal of the lamp is connected by a wire 94 to relay contact 8?. Line wire 9| is connected to relay contact 89. One terminal of lamp TI is connected by a wire 95 to wire 94 and the other terminal of the lamp is connected by a wire 96 to a wire 97 connected to relay terminal 88. One terminal of lamp i8 is connected by a wire 98 to line wire 98 which in turn is connected to relay terminal 86. The other terminal of lamp 18 is connected to wire 91.

It will be seen that the lamps 76, ll and 18 are normally connected in series with the line wires 90 and 9 l, but are connected in parallel with said line wires when contacts 86, El, and 88, 89 close responsive to energization of solenoid winding 80.

Plug 92 is plugged into receptacle 32 and plug is plugged into jack 5? of the main unit. wherebylamps "i6, H, and 18 function in the same manner as lamps H, 18 and Hi, and solenoid 8D is connected in parallel with and is identically controlled with the main relay winding 2!. By the use of multiple outlet connecting adapters at "receptacle 32 and at jack 5?, any reasonable number of auXiliary units in parallel connection with each other and each controlling a bank of photo flood lamps may be used.

It is frequently desirable to employ auxiliary lamps such as those of the photoflash type which reach peak brilliancy faster than the photoflood type after energization thereof. If photofiash lamps are used, they are connected in any reasonable number through multiple outlet connecting adapters, in parallel connection with one another, at receptacle 69 of the basic unit. When the shutter switch i2 is momentarily closed, as above described, the heater winding 63 becomes energized in series with the main solenoid winding 25 and the bimetal arm fill flexes. When the lamps H, l8 and F9 are close to peak brilliancy arm 60 engages stationary contact 65. thereby energizing the photofiash lamps through a circuit comprising wire E4, heater winding 63, contact 62, arm 60, contact 55, wire 66, wire 51, the parallel photoflash lamp circuits connected to socket 69, wire is and wire 46 to the transformer secondary A3. The photoflash lamps flash almost immediately to peak brilliancy, synchronizing with the peak lbrilliancy of gized, to provide synchronization of the peak intensities of the two sets of lamps.

Jack H is employed to control the shutters of a plurality of other cameras when it is desired to use more than one camera to photograph the The other cameras are provided with conventional solenoid-and-plunger means for controlling the operation oftheir shutters-and the solenoid windings thereof are connected in parallel to a suitable male jack plug which is Therefore, when arm 68 flexes into contact with stationary contact 55;as above described, an energizing circuit similar to to contact element 52.

"that; described in connection" with'the use of photofiash lamps is completed and operates the camera shutters, synchronizing their opening with the attainment of peak intensity of the illumination means employed.

Switch 52 is used in conjunction with rheostat ;46 for making preliminary adjustments of the relay contacts of relay device 20 where it is desired to obtain the same resistance in the solenoid winding circuit as is present when the shutter switch i2 is closed. By closing switch 52 and "substituting a portion of the resistance of rheo- -'stat 46, the actual working resistance of the shutter switch circuit may be simulated for purposes of adjusting the relay contacts.

Figure 3 illustrates a form of thermal switch which may be employed at 6! in the arrangement of Figure 1. A metal electrically conducting rod 60' having a substantial temperature cojefiicient of expansion, is rigidly mounted on a suitable stationary support 99. The heater winding 63 is wound around the rod 60'. Secured to rod 60 by a set screw 18!! is an adjustable collar l! adapted to be engaged by a contact element '65 resiliently mounted on a bracket member )2.

Wire 66 is connected to bracket H32. Adjacent to bracket Hi2 and insulated therefrom is a second bracket I03 on which is resiliently mounted a contact element 52'. Engaging contact element '62 is an adjustable collar H34 secured to rod 59 -"by a set screw I05. Wire 59 is connected to rod 6IJ'. One end of heater winding 63 is connected to wire 64 and the other end thereof is connected Windin B3 is electrically insulated from rod 69'. Contact element 62 is normally in engagement with collar IM and contact element 55' is normally out of engagement with collar Iili, When winding 63 becomes energized the rod 60 expands, causing collar ml to engage contact element 65 after a short time period, contact element 62 remaining in engagement with collar Hi4 until another time period 'has elapsed, following which collar l 04 moves out of engagement with contact element 62' where upon the heater winding and the lamp come deenergized, as explained above.

The thermal switch of Figure 3 may be operated without a heater coil by constructing rod 653' of a material having considerable electrical resistance and a high coeflicient of expansion. .Wire 64 is then connected directly to contact 62. The current then passes from contact 62' to collar I04. through red 60 to wire 59. The passage of this electrical current through rod 60 then heats and consequently expands it directly.

Another form of. thermal switch which may be employed at 5! in Figure 1 is illustrated in Figure 4. Pivotally connected at M6 to a suitable support is an electrically conducting lever arm biased in a counterclockwise direction by a spring i953. Counterbalancing spring N38 is a length of resistance wire 63" having a substantial temperature coeflicient of expansion, wire 63" being connected at one end to a stationary terminal W9 and at the other end to the end portion of arm iill, whereby spring I08 maintains wire 63 in tension. When current passes through wire 63 it expands in length allowing spring I88 to rotate arm Hi1 counterclockwise. Arm ill! carries at its free end a first contact H39 which is normally engaged by a contact element 62" resiliently mounted on a set screw H0 adjustably threaded through a stationary terminal I l l. Wire 64 is connected to terminal Ill. 0p-

relays besity.'

posite contact H19 arm [01' carries a second contact H2 adapted to be engaged, upon counterclockwise rotation of arm N11, with a contact element 65" resiliently mounted on a set screw H3 adjustably threaded through a stationary terminal H4. Wire 66 is connected to terminal H4.- Wire 59 is connected to terminal I09.

' When the holding circuit for solenoid winding 2| becomes established, wire 63" is included in the current path between wires 59 and 64, causing wire 63" to expand. After a short time period, during which contact element 62 remains in engagement with contact I09, contact H2 engages contact element 65" establishingthe circuit for the photofiash lamps. After another short time period wherein the two sets of lamps are operating at peak brilliancy and the photographic exposure is being made, contact I09 moves out of engagement with contact element 62' breaking the energiz ng circuits for the lamp relays and interrupting the current flow through wire 63". g By the use of the control devices above described, the process of posing a subject for photography is greatly facilitated inasmuch as the subject can be posed, the lights properly arranged and camera adjustments made while the photoflood lamp or similar lamps are producing illumination by subdued intensity in their series arrangement. During this interval, therefore. the subject is not exposed to the intense heat and light of such lamps producing their maximum illumination. When the camera shutter is tripped to expose the film, the flood lamps automatically produce their full illumination for the exposure of the picture. Theexposure is thus 'made before the subject has time to unfavorably react to the sudden maximum illumination.

Since the lamps automatically revert to their condition of subdued illumination within a short time period, the subject is only exposed to maxiheat and light for a short time. The lamps are operated" at maximum intensity for only short eriods of time thereby extending their useful life. This economic advantage is further enhanced by the fact that the lamps are initially energized at low intensity and when they are connected from series to parallel arrangement for full brilliancy, thermal and electrical shock to the filaments is minimized.

' Further advantages result from the fact that when the-lamps are producing illumination of low intensity before the camera ex osure is made, the various shadows and highlights bear the same relation to each other as when the lamps produce maximum illumination. Thus the photographer may arrange the lights to suit his taste with full "lights at a low intensity will be the same as. recorded on the film at high illumination intenconfidence that the effectshe achieves with the Furthe advantages result from the ability of the device to synchronize and control a plurality spirit of the invention may occur to those skilled in. the art. Therefore, it is intended that no limitations be placed on the invention other than as deflned by the scope of the appended claims.

What is claimed is:

1. In an illuminating system of the character described a pair of control leads, a pair of power leads from an alternating current source, a plurality of flood lamps, a transformer having. two primary leads connected to said power leads and one of a pair of secondary leads connected to one of. the control leads, a relay having a plurality of pairs of contacts and a solenoid also connected by one of a pair of leads to the other of said control leads and connected through the remaining lead of said last-named pair with the other secondary lead of the transformer, a conductor connecting one contact of one pair of the relay contacts with one lead of the solenoid, a second conductor connecting at one end with the other contact of the latter pair of relay contacts and at the other end terminating in a bimetallic switch contact member, a heater coil terminating at one end in a holding circuit contact adjacent to said bimetallic switch contact member, a further conductor connected at one end to the other end of the heater coil and at the other end of the latter conductor to the first-mentioned secondary lead of the transformer, a lead interconnecting one of a second pair of relay contacts with one pole of one of the flood lamps and one of the power leads, another lead interconnecting the second contact of said second pair with one pole each of a second and a third flood lamp, a lead connecting the other pole of the third flood lamp with the other power lead and with one of a third pair of relay contacts, and a lead interconnecting the second of said third pair of relay contacts with the other pole of the first-mentioned flood lamp and the second flood lamp, and switch means for controlling said power leads.

2. In an illuminating system of the character described adapted for use with a camera shuttercontrol switch, a pair of control leads, a pair of power leads from an alternating current source and a plurality of flood lamps-a transformer having two primary leads connected to said power leads and one of a pair of secondary leads connected to one of the control leads, a relay having a plurality of pairs of contacts and a solenoid also connected by one of a pair of leads to the other of said control leads and connected through the other lead of said last-named pair with the other secondary lead of the transformer, a conductor connecting one contact of one pair of the relay contacts with one lead of the solenoid, a second conductor connecting at one end with the other contact of the latter pair of relay contacts and at the other end terminating in a bimetallic switch contact member, a heater coil terminating at one end in a holding circuit contact adjacent to said bimetallic switch contact member, a further conductor connected at one end to the other end of the heater coil and at the other ill end of the latter conductor to the first-mentioned secondardy lead or the transformer, a lead interconnecting one of a second pair of relay contacts with one pole of one of the flood lamps and one of the power leads, another lead interconnecting the second contact of said second pair with one pole each of a second and a third flood lamp, 2. lead connecting the other pole of the third flood lamp with the other power lead and with one of a third pair of relay contacts, and a lead interconnecting the second of said third pair of relay contacts with the other pole of the first-mentioned flood lamp and the second flood lamp, switch means for controlling said power leads, an auxiliary illuminating system, means for conmeeting said auxiliary system with the first-mentioned photographic illuminating system, said last-named means including a jack associated with the latter system having two contacts individually connected to the leads of the relay solenoid and a pair of socket contacts connected to the power leads, and said auxiliary illuminating system including a pair of auxiliary power leads terminating at one end in a plug adapted to be brought into contact with the socket contacts, a plurality of auxiliary flood lamps, an auxiliary relay having two pairs of relay contacts and a second solenoid for operating them and having two leads terminating in two contacts forming a jack plug adapted to be plugged into said jack to connect the second solenoid in parallel with the first-mentioned solenoid, a conductor interconnecting one auxiliary power lead and one pole of one auxiliary flood lamp with one contact of one pair of relay contacts of said second solenoid, another conductor interconnecting one pole each of a second and a third flood lamp of said auxiliary flood lamps and the other contact of said lastnamed pair of relay contacts, a further conductor interconnecting the other pole of each of the one auxiliary flood lamp and the second flood lamp with one contact of the other pair of relay contacts of said second solenoid, and a conductor interconnecting the other contact of the latter pair of relay contacts with the other pole of the third auxiliary flood lamp and the other auxiliary power lead.

GEORGE L. ABRUMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,088,695 Goldensky et al. Mar. 3, 1914 1,295 342 Markley Feb. 25, 1919 1,319,962 Markley Oct. 28, 1919 1,348,746 Schepeler Aug. 3, 1920 1,985,097 Kearsley Dec. 18, 1934 1,988,022 Smith Jan. 15, 1935 2,258,140 Kaletay Oct. 7, 1941 2,261,953 Brown Nov. 11, 1911 2,314,829 Hunter Mar. 23, 1943 

